The present invention relates to a television receiver. Specifically, the present invention relates to a television receiver capable of receiving a television broadcasting signal in two different television broadcasting modes.
As an example of this mode television receiver, there is provided a television receiver capable of selectively receiving either a TV broadcasting (via electric wave) or a CATV (cable television) broadcasting (via cable). Since different bands of frequency are allocated to the above two modes of broadcasting, it is impossible to decide a receiving frequency band unless the broadcasting to be received is previously decided. For the above reasons, it is necessary for a user to set a predetermined change-over switch according to the broadcasting mode to be received.
However, setting of the change-over switch is troublesome for the user. Further, when the change-over switch is erroneously set, it is impossible to receive a desired broadcasting mode. In order to solve the above problems, there have been proposed various arts wherein the television receiver itself can discriminate which broadcasting mode can be received.
An example of such related art is disclosed in Japanese Patent Publication No. 467370B. In this art, attention is given to a point at which channels of the CATV broadcasting are allocated to a specific frequency band to which channels of the TV broadcasting are not allocated. At first, it is searched whether a broadcasting signal exists or not in the specific frequency band. If any broadcasting signal is detected, it is judged the CATV broadcasting is receivable. If not, it is judged the TV broadcasting is receivable. In accordance with the result of judgment, a channel preset operation is executed, and tuning is conducted according to the result of channel preset.
However, the following problems may be encountered in the above conventional television receiver.
In the conventional television receiver, it is judged whether CATV broadcasting or TV broadcasting is receivable only by the existence of the CATV broadcasting signal in the specific frequency band before conducting the cannel preset operation. Therefore, in the case where the existence is misjudged due to the ghost or the like, it is impossible to normally receive broadcasting according to the result of the preset operation. For example, when misjudgment is made in such a manner that TV broadcasting is receivable although CATV broadcasting can be originally received, the channel preset is carried out so that TV broadcasting is receivable. Accordingly, receiving control according to the preset result can not be normally conducted.
The present invention has been accomplished to solve the above problems. It is an object of the present invention to provide a television receiver capable of conducting a more accurate preset processing.
In order to achieve the above object, there is provided a channel preset device in a television receiver for receiving one of two television broadcasting modes having different frequency band with each other, comprising:
signal receiving means for receiving a signal by successively tuning to the respective frequencies of the both broadcasting modes allocated to each of channels;
on-air judgement means for judging whether each of the received signals includes an actual broadcasting signal, and determining a channel in which the actual broadcasting signal is detected as an on-air channel;
count means for counting the number of channel judged as the on-air channel with respect to each of the both broadcasting modes;
mode judgement means for judging a receivable broadcasting mode out of the both broadcasting modes in accordance with the counted number of the on-air channel; and
channel preset means for conducting a channel preset with respect to the receivable broadcasting mode.
Preferably, the two broadcasting modes are a normal television broadcasting using a ground wave and a cable television broadcasting.
In the device, there may be configured that the mode judgement means judges the receivable broadcasting mode in accordance with the numbers of the on-air channel which have been counted by the count means so far each time when the on-air judgement means detects the actual broadcasting signal in the both broadcasting modes in association with the same channel.
The device may further comprise:
memory means for storing a channel number of which the actual broadcasting signal is detected in the both broadcasting modes at once; and
means for setting the judged receivable broadcasting mode judged by the mode judgement means into the channel stored in the memory means.
In the device, there may be configured that: the count means counts the number of the on-air channel with respect to whole the channel of the television receiver; and the mode judgement means judges a broadcasting mode having a larger number of the on-air channels as the receivable broadcasting mode.
In the device, there may be configured that: the count means counts the number of the on-air channel with respect to only the channels to which different frequencies are allocated with regard to the both broadcasting modes; and the mode judgement means judges a broadcasting mode having a larger number of the on-air channels as the receivable broadcasting mode.
The device may further comprise comparison means for comparing the counted number of the on-air channel with regard to one of the both broadcasting modes to a predetermined number. The mode judgement means judges the compared broadcasting mode as the receivable broadcasting mode when the counted number of the on-air channel is larger than the predetermined number.
Preferably, the predetermined number is the minimum estimated number of the on-air channel of the respective broadcasting modes.
According to the present invention, there is also provided a channel preset method for a television receiver for receiving one of two television broadcasting modes having different frequency band with each other, comprising the steps of:
receiving a signal by successively tuning to the respective frequencies of the both broadcasting modes allocated to each of channels;
judging whether each of the received signals includes an actual broadcasting signal;
determining a channel in which the actual broadcasting signal is detected as an on-air channel;
counting the number of channel judged as the on-air channel with respect to each of the both broadcasting modes;
judging a receivable broadcasting mode out of the both broadcasting modes in accordance with the counted number of the on-air channel; and
conducting a channel preset with respect to the receivable broadcasting mode.
Preferably, the two broadcasting modes are a normal television broadcasting using a ground wave and a cable television broadcasting.
In the method, there may be configured that: the receivable broadcasting mode is judged in accordance with the numbers of the on-air channel which have been counted so far each time when the actual broadcasting signal in the both broadcasting modes in association with the same channel.
The method may further comprise the steps of:
storing a channel number of which the actual broadcasting signal is detected in the both broadcasting modes into memory means at once; and
setting the judged receivable broadcasting mode into the channel stored in the memory means.
In the method, there may be configured that: the number of the on-air channel is counted with respect to whole the channel of the television receiver; and a broadcasting mode having a larger number of the on-air channels is judged as the receivable broadcasting mode. In the method, there may be configured that: the number of the on-air channel is counted with respect to only the channels to which different frequencies are allocated with regard to the both broadcasting modes; and a broadcasting mode having a larger number of the on-air channels is judged as the receivable broadcasting mode.
The method may further comprise the step of comparing the counted number of the on-air channel with regard to one of the both broadcasting modes to a predetermined number. The compared broadcasting mode is judged as the receivable broadcasting mode when the counted number of the on-air channel is larger than the predetermined number.
Preferably, the predetermined number is the minimum estimated number of the on-air channel of the respective broadcasting modes.